The proposed research project will experimentally test the effectiveness of an integrated adolescent engagement and family- oriented therapy modality in the treatment of drug abuse. The experimental engagement/treatment intervention is based on the applicants' preliminary studies which demonstrated that the engagement and treatment strategies were both highly effective in reducing drug abuse and increasing adolescent and family functioning in samples of adolescent drug abusers. The proposed study is significant because it allows for testing the effects engagement and intervention separately, together, and in relation to a popular alternative form of therapy, group therapy. Multiple outcome measures have been incorporated to the assessment battery. These measures include assessments of adolescent drug use, engagement into therapy rates, maintenance in therapy rates, adolescent psychosocial functioning, and family functioning. Assessments are obtained from different sources (e.g. adolescent self-reports, parental observational measures, drug lab test results) thus allowing for broader evaluation perspectives. Subjects will consist of 180 Hispanic adolescent (ages 13-18) polydrug abusers and their families. The experimental design will involve random assignment to three intervention conditions: (1) Strategic Structural Systems Therapy (Engagement and Therapy), (2) Strategic Structural Systems Therapy (without engagement), and (3) group therapy. Measures will be obtained before therapy (intake), after therapy (termination), and at two follow-up periods, nine and eighteen months after termination from therapy. Three major research questions will be investigated. The first research question maintaining adolescents in treatment. The second research question addresses the effect of the therapeutic modality on drug use reduction, adolescent functioning, and family functioning. The third research question explores the relationship between improvement in adolescent and family functioning.